Latvia said yesterday it will expel a Russian diplomat for trying to gain secrets about Nato, becoming the third Baltic state this year to throw out Russians suspected of spying on the transatlantic defence alliance.

The Russian Foreign Ministry responded angrily to its sixth diplomat being ordered out of the Baltics in three months, slamming the expulsion as a "provocative" act that reflected an "anti-Russian policy" among Latvian leaders.

The small Baltic states joined Nato late last month and will join the European Union on May 1 to clinch their return to mainstream Europe after more than a decade of post-Soviet reforms since breaking with Moscow rule in 1991.